Device for controlling the dispensing of wax for the creation of tracings and moulds in dentistry

ABSTRACT

A device for controlling and dispensing wax for the creation of tracings and moulds comprising a spatula-like tip ( 3 ), which is mounted on a hollow handle ( 4 ), and a control unit ( 1 ). The hollow handle ( 4 ) has internally a housing ( 10 ) containing a block of solid wax; the housing ( 10 ) communicates with a channel ( 12 ) for conveying the wax into the vicinity of the spatula-like tip; and heating elements ( 9 ) are provided around the housing ( 10 ) for the wax. Preferably, the heating temperature may be regulated by the control unit ( 1 ) via a spirally wound electrical resistance. According to an advantageous embodiment, the spatula ( 3 ) is interchangeable depending on requirements.

The present invention relates to a device for controlling and dispensingwax for the creation of tracings and moulds, particularly useful indentistry for the creation of models of natural teeth.

In dentistry, the creation of wax models of natural teeth, so as to beable to produce therefrom in the most accurate manner prostheses orimplants, is very frequent. At present, the wax for these uses isgenerally sold in special containers, where it is in the solid or in anycase in a dense state. The most common technique, currently available,for creating these moulds consists in applying the melted wax on plasterstumps where the wax cools and solidifies, thus forming the mould. Thisis generally performed using a metal spatula which is heated, usuallyover a flame, and is then immersed in the solid-wax container so as tomelt a small portion thereof. An amount proportional to the dimensionsof the spatula is then removed therefrom and applied, before it coolsand solidifies again, onto the plaster stump where it is modelled inaccordance with the design which is to be obtained. The final mould isobtained by performing a series of subsequent adding operations.

Generally, this procedure involves certain drawbacks which are notinsignificant in nature. Firstly, there is the problem of performingcorrect heating of the tip of the spatula: in fact, insufficient heatinghas the effect that the quantity of wax applied is too small, with thedirect consequence that the number of wax adding operations becomesexcessive, while excessive heating results in too large a quantity ofwax on the spatula which, owing to the small dimensions of the latter,may cause spillage of wax onto the workbench or may produce rough edgesin the mould.

In order to overcome these drawbacks, an electrically heated spatula hasrecently been marketed. This tool comprises a power and regulating unitby means of which the temperature of the spatula is regulated using arheostat, based on the actual requirements at the time, in order toprogram more efficiently the quantity of wax which may be melted in eachcase. The power and regulating unit then transmits the set current to aresistance which surrounds, inside a handle, an extension of the actualworking tip of the spatula. This spatula reduces drastically and in avery advantageous manner the unevennesses in heating of the spatula, butis unable to solve other no less important problems.

Firstly, the wax must be removed, in this case also, from the usualcontainers in which it is sold. Therefore, every time it is required toremove a small quantity from them, resulting in a considerable waste oftime. Moreover, despite regulation of the temperature, relatively largespillage of wax along the path between container and stump still occurs,due to the fact that the wax is transported in the liquid state on asurface, i.e. that of the spatula, which is substantially flat. Finally,as already mentioned, according to all these methods, the mould isobtained by means of subsequent additions of small quantities of wax,such that it is possible to obtain only a layered final structureinstead of a single compact structure.

U.S. Pat. No. A-3,364,577 discloses an electrically heated dental waxshaping and supplying tool having quick-detachable tips. Some tips areshaping tips, while others are nozzles which both supply and shape thewax.

The present invention, which relates to a device for controlling anddispensing wax for the creation of tracings and moulds, comprising aspatula-like tip, which is mounted on a hollow handle, and a controlunit, characterised in that said hollow handle has internally a housingcontaining a block of solid wax in the manner of a replaceablecartridge, in that said housing communicates with a channel forconveying the wax into the vicinity of said spatula-like tip and in thatheating means are provided around said housing, further comprising waxmetering means, characterized in that said wax metering means comprise apushbutton which is located on the outside of the handle and whichextends inside said handle so as to form a horizontal pin which ispivotably hinged with a vertical pin, in turn pivotably hinged on afulcrum and hinged with another horizontal pin which terminates in thematter of a stopper in the bottom part of the wax housing the horizontalpin and the pushbutton being pushed against the action of a spring.

The present invention is now described in greater detail with referenceto the accompanying drawings which show preferred embodiments thereofand in which:

FIG. 1 is a schematic view which shows, overall, the device forcontrolling and dispensing wax according to the present invention;

FIG. 2 is a cross-sectional view which shows the spatula of the device,according to a preferred embodiment of the present invention;

FIG. 3 shows a view—similar to one of FIG. 2—illustrating an alternativeembodiment of the present invention;

FIG. 4 is a cross-sectional view of a detail of the spatula according toan embodiment of the present invention;

FIGS. 5A and 5B show two alternative accessories for the spatula of thedevice according to the present invention; and

FIG. 6 shows an accessory for a preferred embodiment of the presentinvention.

A device for controlling and dispensing wax according to the presentinvention consists of a control unit 1 and a wax dispensing unit 2. Theunit 2, in turn, is formed by a spatula 3 which can be manipulated bymeans of a handle 4. The handle 4 is connected to the control unit 1 bya small pipe 5 for compressed air and an electrical cable 6, both ofwhich are enclosed inside a connecting sheath 7.

The compressed-air pipe 5 terminates in a nozzle 8 located in thevicinity of the spatula 3.

According to the embodiment illustrated in FIG. 2, the electrical cable6 has the function of supplying power to an electrical resistance 9which is spirally wound around a fixed housing 10 inside which a smallround wax insert in a dense or solid state may be inserted—like acartridge—for example from above via a special opening, for subsequentdispensing. Any other known heating device, for example a PTC or thelike, may be provided around the housing 10 in place of a heatingresistance. The bottom of the housing 10 is provided with a unit 11 forthe metered supply of the melted wax, which is of the known type. Themelted wax is then delivered from a special nozzle 12 of the spatula 3.Said nozzle 12 is similar to the needle of a syringe and it is possibleto envisage nozzles of different sizes which are interchangeable witheach other.

The control unit 1 is equipped with a knob 13 for regulating the waxmelting temperature and a pressure reducer 14 for regulating thepressure and, consequently, the flow rate of air leaving the nozzle 8.The presence or not of an air flow leaving the nozzle B is determinedwith the aid of a pushbutton 15, while another pushbutton 16 actuatesthe metering unit 11.

The embodiment shown in FIG. 3 is an improvement to that shown in FIG.2. According to this embodiment, the housing 10 has a small cover 17which can be opened and allows introduction of the wax insert. Moreover,upstream of the block of wax, a piston 18 is provided, which can beaxially actuated inside the housing 10 against the action of a recallspring 19, owing to a compressed-air flow supplied from an additionalpipe 20. A pushbutton 21, for activating the piston 18, and a pushbutton22, for bleeding the said piston, are also provided.

The metering unit 11, according to the present invention, is illustratedin detail in FIG. 4. The pushbutton 16 continues, inside the handle 4,in the form of a horizontal pin 23 which terminates against a spring 24,where it is pivotably hinged at 25 with a vertical pin 26. The pin 26 isin turn also pivotably hinged on a fulcrum 27 and at 28 with a secondhorizontal pin 29 which, in the rest condition, closes the bottom of thecartridge 10 in the manner of a stopper.

In FIGS. 5A and 5B, the spatula 3, underneath the nozzle 12, hasassociated therewith an accessory and interchangeable modelling plate 30which may have different size and shapes depending on the use.

A particularly interesting embodiment of the present invention envisagesa drum 31 (FIG. 6) with a plurality of axial seats 32, each able tohouse a small round wax insert of a type different from the others. Saiddrum is mounted rotatably so as to convey in each case a seat 32 to thelocation of the housing 10 around which the resistance 9 is wound,inside the handle 4. Obviously, the inside of the handle 4 in this caseis modified so as to arrange the heating means 9—which are also modifiedwith respect to FIGS. 2 and 3—around the seat 32 in each case beingused.

When it is required to create a tracing or a mould, for examplecomprising one or more teeth, a wax insert of the desired type isintroduced inside the housing 10. If it is required to use severaldifferent types of wax, the drum 31 may be used; it is then possible torotate the drum until the seat 32 corresponding to the desired type ofwax is conveyed to the location of the housing 10 around which theresistance 9 is wound. When it is required to change the insert, it issufficient to rotate the drum 31 until another seat 32 is brought intoposition coaxial with the resistance 9, and so on.

Once the wax insert has been introduced inside the housing 10, heatingof the said wax is performed by operating the special knob 13 on theunit 1: by setting a higher temperature, a greater degree of melting—andtherefore a faster wax dispensing speed—is achieved, whereas a lowertemperature results in a lower degree of melting and therefore a slowerdispensing speed. In any case, heating of the wax is initiated, the waxthus being gradually melted.

With the embodiment illustrated in FIG. 3 it is possible to achieveparticular advantages. Firstly, when the piston 18 is discharged, it ispossible to open the cover 17 and introduce a wax insert into thehousing 10. All this, obviously, after opening a corresponding coversituated on the outside of the handle 4.

Once heating of the wax block has started, pressing the pushbutton 21causes compressed air to flow from the pipe 20. The compressed airapplies pressure on the piston 18 until the opposing resistance of themelted wax and the recall spring 19 is overcome. At this point, thepiston 18 moves and pushes the insert, thus accelerating the expulsionof the melted wax. The pressure inside the pipe 20, and therefore on thepiston 18, may be regulated by means of a special pressure reducer whichis also present on the control unit 1, while the compressed-air sourcemay be the same source to which the pipe 6 is connected.

With a device such as that illustrated in FIG. 3 it is possible to expelfrom the nozzle 12 also wax which is not completely melted, this beingparticularly suitable for certain processing operations.

In any case, using the handle 4 of the dispensing unit 2, the spatula 3is brought up to the plaster stump (or other point where the wax is tobe deposited) so as to perform dispensing thereof. For this purpose, itis necessary to press the pushbutton 16 which activates the wax meteringunit 11, keeping it pressed for the whole time during which wax is to beexpelled and releasing it in order to stop dispensing.

Pushing the pushbutton 16 moves the horizontal pin 23 of the unit 11 inthe same direction, against the action of the spring 24. By means of thespring 24 it is possible to graduate more effectively the force appliedto the pushbutton and correspondingly adjust more finely thedisplacement of the pin 23. The pivot 25 transmits the movement to thevertical pin 26 which, in turn and by means of the fulcrum 27 and thepivot 28, moves the horizontal pin 29 in the opposite direction to thepin 23. The said pin 29, moving, leaves open a passage on the bottom ofthe housing, which is wider the greater the thrust exerted on thepushbutton 16, in the manner of a stopper. In this way, the wax is ableto flow towards the outlet at a flow rate which is greater the wider thepassage which is left open on the bottom of the housing 10, i.e. thegreater the thrust exerted on the pushbutton 16.

In this way, the wax is able to emerge from the nozzle 12, so as to bespread and modelled. The plate 30 of the spatula 3, which is present asan optional accessory underneath the nozzle 12, allows modelling to beperformed more efficiently.

A small, low-pressure, compressed-air flow may be used in order to causemore rapid solidification of the wax, as it is gradually applied andmodelled. The control unit 1 may, in fact, be connected to acompressed-air circuit (for example to a cylinder or a compressor). Theflow rate of the air is regulated by means of the pressure reducer 14which is present on the unit 1. The air flows through the pipe 5 andemerges at the desired flow rate from the nozzle 8, striking the waxbeing supplied. In this way it is possible to obtain more rapidre-solidification of the wax, so as to prevent wastage of material orthe creation of an unwanted surrounding edge on the tracing or modelbeing prepared.

When operation is to be interrupted, the pushbutton 16 is firstreleased. In this way, the spring 24 pushes the pin 23 and thepushbutton 16 itself outwards. The pin 23 thus brings the pin 26 and thepin 29 into the rest position shown in FIG. 4, closing off, in themanner of a stopper, the bottom of the housing 10 so as to interruptimmediately the outflow of wax. The heating and the compressed air isthen suspended by setting the knob 13 to “0” and discharging thepressure reducers.

If the device according to the embodiment shown in FIG. 3 is being used,the pushbutton 22 is also pressed in order to bleed the compressed airupstream of the piston 18, discharging it. The latter is then broughtinto the rest position by the recall spring 19.

From the above description it is apparent that the device forcontrolling and dispensing wax according to the present invention isable to achieve advantages which were not even imaginable hitherto inthis technical sector. In fact, the wax is dispensed such that attentioncan be focussed solely on the creation of the tracing or mould, withoutwasting time in melting and removing the quantity which is required eachtime. As a result, it is possible to operate not only more rapidly thanbefore, but also under much cleaner conditions, without wastage ofmaterial.

Moreover, owing to the combination of the metering unit 11 with theheating device 9, it is possible to achieve continuous and uniformprocessing, resulting in a product which is of much higher qualitycompared to the present layered products. A further improvement consistsin the additional flow of drying air, which prevents the melted wax fromrunning and therefore allows more precise modelling. Finally, due to thedesign of the assembly consisting of spatula 3 with the nozzle 12 andthe modelling plates 30, it is possible to provide severalinterchangeable spatulas 3, with a considerable increase in versatility.Finally, the use of a drum such as that indicated by 31 in FIG. 6ensures that several different types of wax may be used with the maximumrapidity during the same operation using a single device. Basically,with the device according to the present invention it is possible gainfull control over the wax, from the start to the end of its processingpath, thereby resulting in a revolution in the dentistry sector which iscomparable to the transition from a quill pin to a fountain pen.

It is understood that the present invention may be subject to othermodifications and variations, without thereby departing from theprotective scope thereof. In particular, the systems for regulating theflow rate of the air and wax may be different from those described, andlikewise the heating device may be of any known type. Furthermore, thepiston 18 may be actuated in a manner different from that described.Finally, all the controls have been illustrated as being of themechanical type, but it is obvious that they may be of any other type,such as electronic for example, and that the pushbuttons located on thehandle 4 may also be grouped together on the control unit 1.

1. Device for controlling and dispensing wax for the creation oftracings and moulds, comprising a spatula-like tip (3), which is mountedon a hollow handle (4), and a control unit (1), wherein said hollowhandle (4) has internally a housing (10) containing a block of solid waxin the manner of a replaceable cartridge, wherein said housing (10)communicates with a channel (12) for conveying the wax into the vicinityof said spatula-like tip (3) and wherein heating means (9) are providedaround said housing (10), further comprising wax metering means (11),wherein said wax metering means (11) comprise a pushbutton (16) which islocated on the outside of the handle (4) and which extends inside saidhandle (4) so as to form a horizontal pin (23) which is pivotably hingedwith a vertical pin (21), in turn pivotably hinged on a fulcrum (27) andhinged with another horizontal pin (29) which terminates in the mannerof a stopper in the bottom part of the wax housing (10), the horizontalpin (23) and the pushbutton (16) being pushed against the action of aspring (24).
 2. Device according to claim 1, characterised in that thespatula (3) is formed by a small pipe which is similar to a syringeneedle terminating in a nozzle (12).
 3. Device according to claim 1,characterised in that means for rapid replacement of said block of solidwax are associated therewith.
 4. Device according to claim 3,characterised in that said means consist of a rotating drum (31), whichhas a plurality of axial seats (32) for a corresponding number of waxinserts and which is mounted so that, when said drum (31) is rotated,said seats (32) are located one at a time corresponding with the heatingmeans (9).
 5. Device according to claim 1, characterised in that saidwax metering means also comprise a piston (18) which is located upstreamof the wax insert.
 6. Device according to claim 5, characterised in thatsaid piston (18) comprises a recall spring.
 7. Device according to claim5, characterised in that said piston is actuated by compressed air. 8.Device according to claim 7, characterised in that means (22) forbleeding the compressed air are associated with said piston (18). 9.Device according to claim 1, characterised in that it also comprisesmeans (14; 5; 8) for cooling the wax.
 10. Device according to claim 9,characterised in that said cooling means comprise a compressed-air flowcoming from a compressed-air source which supplies the control unit (1),there being provided in said unit (1) a pressure reducer (14) forregulating the pressure of the air which is conveyed by means of a line(5) to a nozzle (8) which is located in the vicinity of the spatula (3).11. Device as in claim 10, characterised in that said compressed-airsource is a cylinder.
 12. Device according to claim 10, characterised inthat said compressed-air source is a compressor.
 13. Device according toclaim 10, characterised in that the same compressed-air source suppliesthe cooling circuit and the circuit actuating the piston (18).
 14. Useof a device according to claim 1 in dentistry.